XML Elements and Attributes

Elements and attributes are the two ways to put data into an XML document.

Elements

An element is everything from a start tag to its end tag, including what is inside:

<book>
  <title>Learn Web Basics</title>
  <author>Sana Malik</author>
  <year>2025</year>
  <price>950</price>
</book>

An element can contain:

• Text, like <year>2025</year>
• Other elements, like <book> above
• Both, called mixed content: <p>Read <b>this</b> first.</p>
• Nothing, an empty element: <sold-out/>

Attributes

An attribute gives extra information about an element. It sits inside the start tag as name="value":

<book id="B101" language="ur">
  <title>Karachi Ki Kahaniyan</title>
</book>

Attribute values must always be in quotes, single or double. If the value contains a double quote, use single quotes around it:

<quote by='Ali "the teacher" Khan'>Practice every day.</quote>

Element or Attribute?

The same data can be written both ways:

<student gender="female">
  <name>Ayesha</name>
</student>

<student>
  <gender>female</gender>
  <name>Ayesha</name>
</student>

Both are correct. But attributes have limits:

A Well-designed Example

<?xml version="1.0" encoding="UTF-8"?>
<students>
  <student id="S01">
    <name>Ali Raza</name>
    <course>Graphic Designing</course>
    <phones>
      <phone type="mobile">0300-1234567</phone>
      <phone type="home">021-5550123</phone>
    </phones>
    <fee currency="PKR">6000</fee>
  </student>
  <student id="S02">
    <name>Ayesha Khan</name>
    <course>Web Development</course>
    <phones>
      <phone type="mobile">0321-7654321</phone>
    </phones>
    <fee currency="PKR">8000</fee>
  </student>
</students>

Notice:

• The id is an attribute: it identifies the student but is not really "data"
• A student can have many phones, so phones are elements, not one attribute
• currency describes the fee, so it is an attribute of <fee>

A program reading this could print:

S01: Ali Raza, Graphic Designing, PKR 6000, 2 phones
S02: Ayesha Khan, Web Development, PKR 8000, 1 phone

Avoid These Mistakes

• Do not put a list inside one attribute, like phones="0300...,021..."
• Do not use the same attribute twice in one element; it is an error
• Do not use vague names like <data1>, <field2>

Exercise